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Biomedical subjects

K Johnson

Publications and source records attributed to K Johnson.

At least 505 records · Page 28Linked to original sources
PubMed1982

Preparative scale, high resolution purification of low molecular weight DNA fragments.

A commercially available continuous electroelution system has been used to separate and purify low molecular weight DNA fragments from polyacrylamide gels. This method has several advantages over previously reported methods for the recovery of DNA fragments from polyacrylamide gels. This technique, which gives very high recovery rates (80-95%), can be carried out on a relatively large scale and in a way that is not labour intensive. Data are presented for the purification of DNA fragments with molecular weights in the range 1-4 x 10(5) (200-700 base-pairs), although the method is also applicable to larger molecular weight DNA fragments, RNAs and proteins.

Acrylic Resins↗
PubMed1982

Acute osteomyelitis: advantage of white cell scans in early detection.

Acute osteomyelitis was induced in 18 rabbits after direct injection of a solution of Staphylococcus aureus culture into a proximal tibial metaphysis. Serial plain radiographs and radionuclide studies with indium-111 oxide labeled while blood cells and technetium-99m methylene diphosphonate were performed over the next 4 weeks. Visual and quantitative analysis by measuring the isotope activity of 111In and 99mTc over the infected tibias as compared with the opposite bones revealed that the white blood cell scans were positive in 15 (83%) of the 18 rabbits during the first week after injection of the microorganism. During the same period, the 99mTc bone scans were positive in only 22% of the animals (p less than 0.005). In the animals that survived, both white blood cell and bone scans were positive during the second week, and thereafter, the bone scans revealed consistently higher activity than was observed with white blood cell scans. Computed tomography performed in six rabbits revealed an increased attenuation coefficient of the medullary cavities in the infected bones of four animals during the first week and of one more during the second week. Plain radiographs became positive after the 12th day. Results indicate that in patients with suspected acute osteomyelitis, white blood cell scans and probably computed tomography can detect the disease earlier than 99mTc bone scans and plain radiographs.

Animals↗
PubMed1982

Prescriber, pharmacist, and patient interpretation of commonly used prescription directions.

Prescriber, pharmacist, and patient interpretations of commonly used prescription directions were assessed. Results indicated that: 1) Attempts to make directions more time-specific without indicating actual hours for ingestion of the medication tends to lead to patient confusion and potential compliance problems; 2) Some prescribers do not understand the potential interpretation of their own directions; 3) Patients tend to base drug ingestion time on their lifestyles, and unless directions are actually time-specific (e.g., one at 8 a.m., 1 p.m., and 7.p.m.), compliance problems will probably continue; and 4) The prescribed and the pharmacist cannot assume understanding on the part of the patient for nonspecific directions. They must not only reinforce directions, but must also determine the patient's level of understanding, so that actual compliance with the directions intended has a chance for success.

Drug Administration Schedule↗
PubMed1981

Tumor markers in advanced nonseminomatous testicular cancer.

The serum levels of human chorionic gonadotropin (HCG), alphafetoprotein (AFP), lactic dehydrogenase (LDH), and carcinoembryonic antigen (CEA) were measured in 62 men with advanced nonseminomatous germ-cell testicular tumors. The HCG level was elevated in 64%, the AFP level in 67%, and the LDH level in 62%, including three of the six men with normal levels of the other two markers. At least one of these three markers was elevated in 91% of patients. Sustained or rising levels of HCG or AFP always were accompanied by persistent or recurrent tumor. Carcinoembryonic antigen was found not to be a useful marker in testicular cancer. Patients whose tumors contained yolk-sac elements always had elevated AFP levels, and patients with choriocarcinoma always had elevated levels of HCG. However, absence of these histologic types did not preclude elevations of the respective markers. Tumor markers are indispensable in the management of patients with testicular cancer, and several markers must be measured repeatedly if the greatest percentage of patients is to benefit.

Adolescent↗
PubMed1981

Human chorionic gonadotropin and alphafetoprotein in the staging of nonseminomatous testicular cancer.

Thirty patients with nonseminomatous testicular cancer and no evidence of metastases outside the retroperitoneum were evaluated for discrepancy between the clinical and pathologic stages and also for frequency of elevations of the serum levels of human chorionic gonadotropin (hCG) and alphafetoprotein (AFP). When marker-level data were not considered in the staging, the clinical and pathologic stages differed in 47% of the patients; the inclusion of marker data reduced the staging error to 37%. Seven of ten patients with clinical Stage I, pathologic Stage II disease had normal marker levels (false-negative results). However, there were no false-positive results: abnormal marker levels before retroperitoneal lymphadenectomy always signalled persistent tumor unless the level could be accounted for by the metabolic decay rate of marker produced by the primary tumor. Comparison of marker-level data from these patients with data from 48 patients with Stage III disease demonstrated increasing frequency of elevated marker levels with increasing stage (P less than 0.001). Serial determinations of HCG and AFP are helpful in clinical staging and are necessary in clinical management.

Chorionic Gonadotropin↗
PubMed1981

Aversive effects of naltrexone in subjects not dependent on opiates.

Naltrexone was given to ten opiate-free volunteer subjects following the same dosage schedule used for initiating treatment of opiate-dependent persons. During the three-week initiation period, three subjects dropped from the study owing to aversive effects of the drug. The remaining seven subjects reported similar unpleasant but tolerable effects. A separate group of ten volunteer subjects was given single doses of 50 or 100 mg of naltrexone or a naltrexone placebo on three separate occasions using blind controls. These subjects also reported aversive effects. The principal symptoms reported were loss of energy, gastrointestinal disturbances and mental depression. It is possible that these aversive reactions of naltrexone have limited acceptance of the drug as a treatment for opiate-dependent persons.

Adult↗
PubMed1981

Radionuclide angiographic correlation of the R wave, ejection fraction, and volume responses to upright bicycle exercise.

The change in the R wave and the response of the ejection fraction to upright bicycle stress testing with radionuclide angiographic studies were determined for 18 control subjects and 29 patients with coronary arterial disease (70 percent stenosis or more). In the control group, all had an increase in the ejection fraction from 64.8 +/- 7.7 to 75.7 +/- 9.4 percent with stress (P less than 0.01). All control subjects had a decrease in the R wave with exercise. In the group with coronary arterial disease, most patients had a decrease in the ejection fraction averaging from 63.5 +/- 10.9 to 58.6 +/- 12.8 percent (P less than 0.01). An appropriate response of the R wave and ejection fraction (decrease in R wave and increase in ejection fraction or increase in R wave and decrease in ejection fraction) occurred in 23 (79 percent) of 29 subjects (P less than 0.005). The sensitivity, specificity, and predictive value for the response of the ejection fraction were as follows: 83 percent (24/29); 100 percent (18/18); and 100 percent (24/24). Of the patients with coronary arterial disease and an increase in the R wave, 17 (94 percent) had multivessel disease, while six (55 percent) of 11 with a decrease in the R wave had multivessel disease (P less than 0.05). The systolic volume decreased in all control subjects by -15.9 +/- 8.6 units (P less than 0.01) and increased in most of the group with coronary arterial disease by 13.7 +/- 17.8 units (P less than 0.01) in response to stress. There were 20 of 29 patients (P less than 0.05) with an appropriate response of the R wave and systolic volume to stress (increase in R wave and systolic volume or decrease in both). The change in the R wave did not correlate with the change in the diastolic volume with stress (P greater than 0.05). Changes in the R wave with exercise correlate with the change in the ejection fraction (and hence ventricular function) and with the changes in systolic volume, which may be one of the mechanisms of the response of the R wave, suggesting that the change in the R wave is related to changes in contractility. Increase in the R wave with stress suggests multivessel coronary arterial disease.

Adult↗
PubMed1981

Retinol esterification in lamb kidney.

Retinol esterification was demonstrated in vivo and in vitro in lamb kidney. Retinol labeled with hydrogen-3 injected into the renal artery of lambs appeared in the labeled retinyl ester fraction in the renal vein. Degree of tracer incorporation into retinyl esters increased with vitamin A intake. In homogenates, activity was concentrated in microsomes and enhanced fourfold by addition of adenosine 5'-triphosphate and coenzyme A to the incubation mixture. These findings suggest that the esterification is a function of fatty acyl coenzyme A:retinol acyl transferase. Renal esterification may play a role in retinol homeostasis.

Animals↗
PubMed1981

Raynaud's phenomenon: a common toxicity after combination chemotherapy for testicular cancer.

Raynaud's phenomenon occurred in 22 of 60 men (37%) treated with vinblastine and bleomycin with or without cisplatin for germ cell testicular cancer. An additional six patients (10%) had symptoms suggestive of Raynaud's phenomenon. Patients with and without Raynaud's phenomenon did not differ with respect to median age; tumor histology; total doses of vinblastine, bleomycin, and cisplatin; or the frequency of vinblastine-induced neuropathy and bleomycin-induced cutaneous toxicity. Digital ischemia occurred in 21% of patients treated with only vinblastine and bleomycin, and in 41% of patients treated also with cisplatin. Cigarette smoking was commoner in patients with than in those without Raynaud's phenomenon. Hand arteriograms showed diffuse arterial narrowing and abrupt vascular cutoffs. Except for one patient with a very low titer of cold agglutinins, no patient had detectable antinuclear antibody, rheumatoid factor, cryoglobulins, or cold agglutinins. Raynaud's phenomenon is a common delayed toxicity after chemotherapy with vinblastine, bleomycin, and cisplatin in patients with germ cell neoplasms.

Adolescent↗